Research suggests that regular exercise may brighten the mood of people with chronic health problems like cancer and heart disease. But statistically, on average it is only effective for one in six people.

Still, it’s evidence that the benefits of regular exercise are more than physical.

Dr. Alan J. Gelenberg, who chairs the department of psychiatry at Penn State told Reuters that there is evidence that exercise is useful in the prevention of and treatment for depression.

Research from 90 previous similar studies found that people’s depressive symptoms, as rated on a variety of psychological scales, dropped about 22 percent with exercise overall.